In lighting technology, especially in ground vehicle lighting, there is a need to perform multiple light functions on one, i.e., common surface, whereby one light function requires large light scattering and high light homogeneity, whereas the other function requires low light scattering, low light homogeneity and high luminous efficiency, etc. At the same time, however, it is advantageous if the light sources of both different light functions are located on the same carrier, even better in one plane.
There are known flat-shaped light guides with an assembly of collimating elements for leading in light from LED light sources and for emitting the collimated beam in the desired direction. A light scattering filter is placed in the direction of propagation of light beams to scatter the light beams. The disadvantage is that even this light scattering filter does not provide such uniform (homogeneous) light distribution as in the case of direct propagation of light beams from a LED light source to the light scattering filter. This is due to the fact that the light scattering angle from the LED light source is up to 180°, which in a combination with the light scattering filter disposed at a certain distance from the light source ensures a sufficiently homogeneous distribution of the light only when the light from the light source is guided directly into the light scattering filter, but does not guarantee sufficient homogeneity of a collimated light beam.
From US 2016 334 074 A1, a lighting device device is known which includes a plurality of LED light sources and a lens unit which is positioned in a corresponding manner relative to the LED light sources. The lens unit includes a transfer lens, a first totally reflective lens and a second totally reflective lens, whereby the light incident surface and the light emitting surface of the transfer lens, as well as the light incident surfaces and light emitting surfaces and the surfaces with total reflection of the first totally reflective lens and the second totally reflective lens are biaxial anamorphous aspherical surfaces. A micro lens field is formed at least on one the light incident and light emitting surface of the transfer lens. The disadvantage of this arrangement is that it does not solve the problem of performing a pair of different light functions in one output surface.
A similar device is disclosed in US 2009 207 610 A1, which describes a lighting system with a common optical system to perform a pair of light functions in one output surface, e.g., a rear fog light and a rear position light. The lighting system includes a light guide, which has a first side and a second side, whereby the first side of the light guide has a plurality of optical elements formed therein, the optical elements being associated with light sources. The optical element reflects and substantially collimates light beams emitted from the light source via the light guide to form the desired light pattern depending on whether the optical element is associated with the first or second light source. The disadvantage of this arrangement is the inability to achieve the required lighting performance for each of the light functions.
It is an object of the invention to eliminate or at least minimize the drawbacks of the background art, in particular to allow to perform a pair of light functions in one, i.e., a common surface, where one light function requires large angle light scattering and high light homogeneity, but for the second light function low angle light scattering is required, low light homogeneity is sufficient with the advantageous location of the light sources of the two different light functions on the same, i.e., common carrier, preferably in one plane.